Fish knife

maintenance, care, compatibility

Apteronotus white-eyed (Latin Apteronotus albifrons) or as it is often called – a black knife, this is one of the most unusual freshwater fish, which fans keep in aquariums.

Love her for the fact that she is beautiful, interesting in behavior and extremely unusual. At home, in the Amazon rainforest, local tribes believe that the fish of the knife, after the death of the ancestral spirits, so it is considered sacred.

Although they can grow quite large, about 40 cm, they remain very elegant. A little shy by nature, the apteronotuses adapt with time and begin to behave bolder, to the point that they feed from the hands.

For a long time, all apterotuses marketed were exported from South America, mainly from Brazil. But in recent years they have been successfully bred in captivity, mainly in Southeast Asia, and the pressure on the population in nature has dropped significantly.

The fish black knife was first described by Karl Liney in 1766. It lives in South America, in the Amazon and its tributaries.

The white-cap apteronotus is also called the black knife, and the black ghost fish knife in English Black Ghost Knifefish.

In nature, it lives in places with a weak current and a sandy bottom, migrating to flooded mangrove forests during the rainy season. Like most fish of its kind, loves densely overgrown places with plenty of shelter.

In the Amazon, the places where the apronotus dwells, are poorly lit and have very poor eyesight. To compensate for the weakness of vision, the white-rimmed produces a weak electric field around itself, with which it captures movement and objects. The field helps to hunt and navigate, but in addition, with the help of electricity, the apteronotus communicates with its own kind.

Black knives are nocturnal predators that prey on insects, larvae, worms and small fish in rivers.

30 cm black knife:

Black knives are predatory fish. In nature, activity occurs at night, when they prey on insects, worms, snails and small fish.

In an aquarium, live or frozen food is eaten, for example, bloodworms, shrimp meat, artemia or tubule, fish fillets, can also be taught to various tablets and granules. They will also hunt small fish, which can be fed knives.
It is better to feed in the evening or at night, but as you get used to it, they can feed during the day, even with hands.

Peaceful fish in relation to medium and large-sized fish, fish and invertebrates which can swallow, perceived as food. However, they can be aggressive towards fish of their own kind or other types of knives, it is better to keep in the aquarium one white-boiled apteronotus, without congeners.

Black knife fish: content, compatibility, breeding, photo-video review

Apteronotus white-fronted (black knife) – these fish in recent years are becoming increasingly popular among domestic aquarists. The fish was first introduced and appeared in our aquariums in the early 80s. She won the hearts of both professionals and beginners due to her beauty and graceful movements.

And of course the possibility of combining it with many other species of fish makes it more and more attractive for keeping in a home aquarium.

Latin name: Apteronotus albifrons
Squad: Gymnotoobraznye (Gymnotiformes)
Family: Apteronotaceae (Apteronotidae)
Water temperature: 23 – 28 ° С
PH Acidity: 6.0 – 7.5 °

“Stiffness” dH:
5 – 15 °

Aggressiveness:
thirty%

The complexity of the content:
Lightweight Compatibility: Black Knife – Apteronotus, a bottom, relatively peaceful fish, but at the same time carnivorous. Black knives show intraspecific aggression in the struggle for territory, especially males.

To the rest of the neighbors in the aquarium are indifferent. Fish black knife, reaches a rather large size – in nature up to 50 cm, and in an aquarium up to 30-40cm. therefore, it is recommended to keep it in one copy in an aquarium from 150 liters. with any peace-loving fish medium and large sizes. Very mobile and nimble fishes, such as barbs, can cause disgusting shy knives and pinch their delicate fins, and such as, for example, neons and guppies, Apteronotuses can be mistaken for food.

For compatibility with other fish, see the article. compatibility of aquarium fish.

How many live: With optimal conditions in the home aquarium, Apteronotuses live up to 12 years. Find out how much other fish live IN THIS ARTICLE!

The minimum volume of the aquarium: from 150l., it is possible to plant one individual of this species in such an aquarium. With good conditions, Apteronotus reaches impressive size, so it’s better to immediately buy an aquarium from 200-250 liters.

About how much you can keep fish in X liters of aquarium, see HERE.

Requirements for care and maintenance: as you already understood, for the content Black knife you need a large aquarium with clean water, always with a lid, because fish can jump out. As for other types of fish, they need to create conditions close to natural.

For this, the aquarium should be equipped with good filtration, preferably a peat filter, active aeration and weekly water changes up to 30-35% of the total volume of the aquarium. Also in the aquarium should be placed various shelters – snags, grottoes, desirable planting plants forming dense thickets, so that the fish can hide during the day, as it leads mainly nocturnal.

The lighting can be bright, rather for plants, and for fish the light should be faint, diffused, to which the vision of the fish is optimized, so you need well-shaded areas where Apterotics could hide from bright light in the daytime.

Feeding and diet: The apteronotus is a white-felled carnivorous and, under natural conditions, mainly feeds on insect larvae and fry of other fish. In terms of domestic content, in principle, nothing changes, they willingly eat both live and frozen food – bloodworm, strawberry, do not refuse to eat sliced ​​shrimps and squid, and of course they will not miss the moment to have dinner with fish fry.

For this, be careful when breeding your other aquarium pets, do not leave the fry in the general aquarium, otherwise they will have dinner. It is extremely rare to take dry food and substitutes. It is recommended to feed black knives before turning on the aquarium lighting, or after turning it off once a day.

Overeating for fish is extremely dangerous due to the structure of the intestines of fish. A blockage of the intestine can lead to its death, so it’s better not to feed than to overfeed, and in your aquarium, in any case, it will find something to eat.

When searching for food Apteronotus focuses on changes in the electromagnetic fields, fixed by special receptors located along the entire length of the body.

Feeding aquarium fish must be correct: balanced, diverse. This fundamental rule is the key to successful keeping of any fish, be it guppies or astronotuses.

Article “How and how much to feed aquarium fish” talks in detail about this, it outlines the basic principles of the diet and feeding regime of fish.

In this article, we note the most important thing – feeding fish should not be monotonous; both dry and live food should be included in the diet. In addition, you need to take into account the gastronomic preferences of a particular fish and, depending on this, include in its diet ration either with the highest protein content or vice versa with vegetable ingredients.

Popular and popular feed for fish, of course, are dry food. For example, hourly and everywhere can be found on the aquarium shelves of food company “Tetra” – the leader of the Russian market, in fact, the range of feeds of this company is striking.

In the “gastronomic arsenal” of Tetra are included as individual feeds for a certain type of fish: for goldfish, for cichlids, for loricarids, guppies, labyrinths, arovan, discus, etc. Also, Tetra has developed specialized foods, for example, for enhancing color, fortified or for feeding fry.

Detailed information on all Tetra feeds, you can find on the official website of the company – here.

It should be noted that when buying any dry food, you should pay attention to the date of its production and shelf life, try not to buy food by weight, and also keep the food in a closed state – this will help avoid the development of pathogenic flora in it.

In nature, live: Black knives come from South America, live in slowly flowing, muddy, overgrown reservoirs of the upper and middle parts of the Amazanka river basin – Brazil, Colombia, Peru, Bolivia and Paraguay Parana River. The size of the fish reaches 50 cm.

Description of the black knife

Are nocturnal – carnivorous. They belong to weakly electric fish with passive electrogenesis.

Due to the lack of good vision, they use their abilities to search for food, orientation in space and protection. The content of these fish does not represent any danger to people and other inhabitants of the aquarium, it is necessary to take into account the proportionality with other types of fish.

In captivity, the white-fronted Apteronotus reaches up to 40 cm. in length. The body of the fish is black, stretched in length, flattened laterally, narrowed to the tail, the mouth is terminal, the head is large with a white spot, sometimes leaving a stripe along the back. On the long tail stem there are two white-yellow transverse strips, the tail fin is small.

Dorsal and ventral fins are absent, adipose – filiform. The anal opening is located closer to the head, next to the mouth.

The anal fin is well developed, stretches from head to tail, with which the fish can swim in any direction (front, back, side) at approximately the same speed. In black knives, intraspecific aggression in the struggle for territory is acute, especially in males. Therefore, it is recommended to keep them in a single copy, but if it suddenly happens that there are two or more fish of this species in your aquarium, then you should equip it with a sufficient number of shelters, but it will not do without fights anyway.

Fish are scaleless, therefore they are more susceptible to diseases such as ichthyophthyriosis. The treatment does not recommend the use of drugs containing zinc.

Breeding and sexual characteristics of the fish black knife: White-fronted Apteronotus – fish is quite difficult to breed. The first offspring was obtained in Leningrad in 1990.

It reaches its sexual maturity at the age of 1-1.5 years. Gender signs are almost not detected, the female is smaller in size with a more rounded abdomen, in males the presence of a fat cone on the head. A spawning flock with a predominance of males, for this purpose, a spawning aquarium of 100 liters is taken. Pista or synthetic threads are suitable as a substrate.

Spawning is stimulated by lowering the water level followed by an increase in distilled water, imitating the rainy season, the water temperature is 25-26 ° C, and the lighting is weak. It is recommended to install several nozzles that create a strong flow of water, spawning occurs usually at dawn in its stream.

The water in the incubator should be well saturated with oxygen. The female sweeps up to 500 large yellow, rather sticky eggs.

After spawning, producers are recommended to be transplanted, otherwise the caviar will be eaten, the incubation period lasts up to 96 hours. Fry appear that can swim and eat zooplankton.

With proper maintenance and feeding, the young grow rapidly and by the month reach 5 cm and take the shape and color of adult fish.

Video about fish “Black Knife”


There are cases when a person, having gained experience in breeding and maintaining a standard set of ornamental fish, wishes to acquire some unusual inhabitant for his home aquarium. Fortunately, in pet stores or in aquarists’ societies, you can buy quite rare representatives of aquatic fauna, one of which is knife fish or, according to scientific terminology, a black knife.

The name itself sounds ominous, but the character of the knife fish cannot be called aggressive, and its content does not pose a direct threat to other inhabitants of the domestic water reservoir. In addition to fry and small fish, of course, which she can easily take for food.

By the way, in this particular case, its behavior differs little from the habits of other ornamental fish.

In its appearance, the fish completely corresponds to the name: the black body, stretched out and strongly compressed from the sides, is really shaped like a knife.

The similarity is enhanced by the presence of a long black fin in the lower part of the body, which stretches from the base of the large head to the tail. It is due to this fin, as well as two small pectoral fish-knife and moves in the water.

It has no dorsal and separate ventral fins, which distinguishes the Knife black from most aquarium fish.

Another significant feature is the complete lack of scales, like the well-known eel.

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